Electric welding apparatus



T. E. MURRAY, JR.

ELECTRIC WELDING APPARATUS.

APPLICATION FILED MAY 2, 1919.

1,320,894. Patented Nov. 4, 1919 51 vwewtoz alto Mun M X A UNITED STATESPATENT, oFFIcE.

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OF 3300mm, NEW YORK.

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' I I Application filedS Iay 2,

' To all whom it mag concern:-

' \Velding' is a specification.

Be it known that I, THOMAS E. MURRAY,

J12, a citizen of the United States, residin at Brooklyn, in the countyof Kings an State of New York, have invented a certain new and usefulmprovement in Electric pparatus, of whichthe following In electricallywelding together two objects by a current traverslng the. joint, certaindifiiculties arise, the effect of which, generally stated, is tow'makethe Weld not uniform throughout the welded areas. As a consequence,there may be localized portions of said areas Where the weld is,relatively speaking, imperfect as compared with the i remaining orintervening portionsthis bemg due to an unequal distribution of thewelding current, which in some places may be of less strength'than isrequired pro erly to heat :"the metal, or I in others 0 in orburninglthe metal. These conditions chiefly develop" with an increase ofthe area of the weldedsurfacesor'when a change of shape thereof is made,whereby while the area remains constant, it becomes elongated one endthereof, that current will not be equal] distributed, because some of 1twill" pass irectl to the joint in a line perpendicularto t e plane ofthejomt, while the rest will reach the joint in lines at an angle tosaid plane, these angles diminishing in accordance with the lengthoftube traversed. Therefore, the resistance offered by the workto thepassa e of the current will increase from one cm .of the'tube to theother, and the heating effect Wlll propor tionately decrease, and thelonger the tube, the greater this decrease will be at one 'endas'compared with the other.

Agam assume, the sections to taper, so

that the resulting tube will not of too- 1 great strength, with theresult of overheat Specification of Letters Patent. Patented Nov. 4,1919.

1919; Serial no. 294,298? f formbut ofarying diameter. Thenif thesectlons be seated in correspondingly shaped recesses in the opposingfaces of two cubical electrodes, the current will traverse a shorterdistance in reaching the larger end of the tube'than in reaching thesmaller end, with corresponding variations in resistance and heatingefiect;

Again assume under the above stated'condition of a tube of uniformdiameter, the

character of the'metal varies over certain.

localized areas, so that a difference of. resistance to the passage ofthe current results at these areas as compared with the resistanceelsewhere. Corresponding variations in heating effect will follow. Againassume that while the external diameterof'the tube is uniform, theinterior \diameter is hot. Then the'current in reaching the joint willpass overpaths in the metal longer in some places than in others, with,as before, variations in heating efi'ect. Again assume that throughslightdeformations of the sections, they do not accurately fit the,electrodes, so that. at some points they are in close contact, and inothers separated. There will be greater resistance at the air gaps orplaces of imperfeet cont-actthan elsewhere, and corresponding variationsin heating effect will ensue.

' The foregoing examplesand might be addedwilh be sufficient to show thenature of the problem which my present invention solves, namely, despiteconditions suchas above stated, which normally cause an irregularity incurrent distribution,

at the joint'and consequent corresponding differences in heating eifect,to provide means whereby such conditions are neutralized or overcome,and either a uniform dis tribution of heating effect to a degree sufiicient for all practical purposes is achieved, or where it is desired thata certain part or parts of the joint may be more or less heated thananother part or parts, that result can also to a degree sufficient forall purposes be accomplished. j

In order to illustrate my invention, I here show an a paratus for,welding the lon 'tu dinal hal A g diameter, uniform thickness and of"homopractical geneous metal, in which I can distribute'the current overlocalized areas of the joint.

' In the accgmpanying drawmgs- Figure 1 is a transverse section on thehue 1, 1 of Fig. 2-through the welding electrodes sectionsof a tube of.uni Om others and one ofthe transformers, the upper movable electrodebeing shown partly broken away, and its operating mechanism beingomitted. Fig. 2 is'a sectionon the line 2, 2

of Fig. 1. Fig. 3 is a side elevation of, a

. portion of the gore, four of the transformer.

parts.

secondaries, and portions of the electrodes.

Similarletters of reference-indicate like,

'A'is the upper welding electrode, {which is to be provided with anysuitable mechanism for moving it toward and from the lower fixedelectrode B. In said electrodes are registeringsemicircular recesses, in

which respectively are seated two longitudinal half sections C, C of atube of uniform diameter.

. E, F, G, H, I, J, are' thesecondaries of a seriesof transformers. Eachsecondary comprises an upright pillar L, from the lower side of whichextend integral arms M, first horizontal, then Vertical and thenturnedinwardly, with their inturned ends separated by air -gaps from thevertical edges of the flanges Non the upper end of pillar'L. In each ofthe loops formed by the arms M is a primary coil 0, so'that there aretwo series of coils, one series on each side of pillar'L. Through allthe coils on one side passes a core P, and through all the coils on theopposite side passes a core Q.

7 The ends of the cores P, Q, which protrude beyond the outside coils ofthe two series are turned toward one another, and preferably meet. f

- The primary coils O on the right hand side of Fig. 1 are connected inbranch 'circuits'to the leads R, S, which come from the source ofwelding current. In each branch is interposed a switch T, so that anysingle coil, or any group of coils, can be cut out of per electrodeAconnected in any suitable way which will permit of its free upward anddownward movement to each of the secondary ,arms M. I here showsuch'connections made by flexible wires U, V.

a While Ihave represented in Fig. 2 but seven transformers, it will beobvious that any number may be used, placed succes sion, as shown, thecores P, Q being corre spondingly elongated. This number" will .dependupon the length of the work to be welded. So also the number oftransformers Wlll depend upon the desired'degr ee of variation incurrent distribution.

In 'such case the connection of the elec the metal uniformly "brought towelding trodes -to -the source of welding current is arbitrarily made,it may happen that the current will .be unequall distributed at thejointor, in other wor s, exercise a different heating effect at somelocalized areas or trodes, I can distribute the current so that theelectrodes will be uniformilyheated and condition over the whole j oint.

If it be desired to confine the-heating ef- I feet to certain localizedareas, I may do this by cutting out one or more transformers, orarranging them in groups to actupon the localized areas only. One way ofdoing this which I here illustrate, is'the provision of a switch T, asdescribed, in the circuit of each primary coil, whereby the transformercon- 7 trolled may be cut out. Other ways, such as the cutting out ofsome of the turns ofa I given primary, will readily suggest themselvesto anyelectri'cian. It is known, for example, that-where two elongatedobjects are disposed with their ends exposed to the air, the coolingeffect of the atmosphere is apt to cause imperfect joints at such ends.

In such case, I should energize the two end transformers, even if asufficient distribution of heating effect over the. bodies of theobjects were found obtainable with a less' number than all of theintermediate transformers. Again, instead. of welding two long sectionstogether by-a current discharge through all of the branch connectionssimultaneously, I may do so by closing the transformer primary circuitssuccessively, thus concentrating the whole current upon successivelocalized areas. I claim: T

1 :An electric welding aipparatus comprising two coeperating weldingelectrodes, and means for controlling the welding current traversing thejoint between the bodies to be welded to .heat the same over a certainpredetermined localized fractional area of said joint I I 2. An electricwelding apparatus, comprising two coiiperating welding electrodes, andmeans for controlling the welding curr'ent traversing the joint betweenthe bodies to be weldedto heat the same over a pluralityof predeterminedlocalized fractional 1 areas of said joint.

.. 3. An electric welding; apparatus, comwelded to cause said current topass through I prising two cooperating welding electrodes,

be welded from one to another predeter mined localized fractional areasof said joint. I

4. An electric welding apparatus, comprising two cooperating weldingelectrodes, and means for dividing the welding current traversing thejoint between the bodies to be a plurality of predetermined localizedfractional areas of said joint. 7

5. An electric welding apparatus, comrisin two coo eratinw weldinelectrodes a a n 3 one of said electrodes being fixed and the othermovable, a support of conducting material in contact with said fixedelectrode and means for directing the welding current throughpredetermined localized fractional areas of said support.

6. An electric welding apparatus, comprising two cooperating weldingelectrodes,

one of said electrodes being fixed and the other movable, a support ofconducting material in circuit with said electrodes, with which supportsaid fixed electrode is in contact, and means for dividing the weldingcurrent traversing said support.

7. An electric welding apparatus, comprising two cooperating weldingelectrodes,

' a plurality of branch circuits for conveying the welding current tosaid electrodes, and current controlling means in each of said branchcircuits.

8. An electric welding apparatus, comprising two cooperating weldingelectrodes,

a plurality of transformers having corre sponding secondary terminalselectrlcally connected to one of said electrodes, and

' means for energizing independently one or more of said transformers.

9. An electric welding apparatus, comprising a plurality of transformershaving portions of their secondaries disposed with their correspondingpolar surfaces in the same plane, a fixed welding electrode in con.-tact with said surfaces of said secondaries, and a movable electrodecooperating with said fixed electrode.

10. An electric welding apparatus, comprising a plurality oftransformers having portions of their secondaries disposed with theircorresponding polar surfaces in the same plane, .a fixed weldingelectrode in contact with said surfaces of said secondaries, a movableelectrode cooperating with said fixed electrode, and means forindependently energizing each of said transformers.

11. An electric welding apparatus, comprising a fixed welding electrode,a movable welding electrode cooperating with said fixed electrode, aplurality of transformers having their primary coils in branch circuitwith the source of welding current, and each having a secondarycomprising a stationary pillar and an arm in loop form extending fromone side thereof, the said fixed electrode being in contact with andresting upon and extending transversely across said pillars, and thesaid movable electrode being in branch circuit with each of said arms,and means for independently controlling the welding current in each ofsaid primary branch circuits.

12. An electric welding apparatus, comfixed electrode, a plurality oftransformers having their primary coils in branch, circuit with thesource of welding current, and each having a secondary comprising astationary pillar and an arm in loop form extending from the sidethereof, said primary coils being inclosed in said arms, and the saidfixed electrode. being in contact with and resting upon and extendingtransversely across said illars, and the said movable electrode being inbranch circuit with each of said arms, a core extending through saidprimary coils, and means for independently controlling. the weldingcurrent in each of said primary branch circuits.

In testimony whereof I have affixed my signature in presence of twowitnesses.

